1. Field of the Invention
The present invention relates to dental replicas and, more particularly, to a method for mounting dental replicas and to a base plate assembly for mounting replicas.
2. Description of the Prior Art
When a dentist determines that a patient requires a crown, bridge, inlay or other common dental prostheses, it is necessary that the dentist first obtain a negative impression of the patient's teeth and gums, including the negative impression of the dental quadrant or quadrants containing the affected teeth. Dental impressions may be unilateral, bilateral, upper or lower, etc. depending on the work to be done. This is customarily accomplished by having the patient bite into a mass of yieldable, rubber-like impression material carried on a holder so that a mold cavity of teeth and associated gums is created. The material will cure in a short time and retain an exact impression of the patient's teeth and gums. This negative impression will then be sent to a dental technician who will use it in any of a variety of conventional techniques to arrive at a stone cast dental replica. The cast replica is mounted in such a way to allow individual replicas of affected teeth, such as the tooth needing a crown or cap, to be segregated from the greater replica. This individual segment is ordinarily removed and repositioned into the greater model several times as work progresses to ensure that the end product being fashioned has proper alignment and visual conformity with the greater model.
Preparation of the negative dental impression is a well known preliminary step, however there are a variety of techniques and devices employed by the dental technician in processing the negative dental impression into a stone cast replica that is mounted in a fashion suitable for work on the individual removable dental segments. Unfortunately, none of the conventional and prior art methods and devices are without limitations and drawbacks. For example, several well established prior art techniques require two pourings of mold material, one for the die stone replica of the teeth and gums, and another for the formation of the base upon which the replica is attached. Oftentimes the base of the replica must undergo grinding to from a flat surface in which drill hole locations must be located and marked. Special drilling equipment is then used to drill holes, and dowel pins are then selected and mounted in the holes by use of adhesive. In many cases sleeves are applied to the mounted pins and the sleeved pins inserted into the uncured base which dries to retain the embedded sleeves. Such techniques are inevitably tedious and time consumptive, as well as consumptive of materials and supplies. It is also noted that the special electrically powered equipment represents an appreciable cost outlay. Additionally, special training and skill of the technician must be relied on in order to properly implement such techniques.
U.S. Pat. No. 4,122,606 is an example of a two-pour system that involves the drilling of holes and the use of dowel pins, etc. U.S. Pat. Nos. 4,767,330, 4,398,884 and 3,937,773 purport to bring certain improvements to the industry. Nevertheless, each of these disclosures requires the steps of making two molds and bring associated costs in labor, material, supplies and time. It is also noted in these prior art techniques that a die stone surface of a removable tooth segment must be brought into engagement with another stone cast surface or with a rigid plastic surface every time the segment is replaced in the greater replica. This can lead to an abrasion of the die stone and a loss in the integrity of the fit.
The prior art also includes some one-pour techniques that avoid some of the aforestated drawbacks. For example, U.S. Pat. Nos. 4,371,339, 4,368,042 and 4,721,464. It is noted, however, that U.S. Pat. No. 4,721,464 involves the positioning and aligning of individual dowel pins and guides, and die stone surfaces must be brought against hard plastic surfaces. U.S. Pat. No. 4,371,339, even though it employs a special base element for releasably supporting its dental replica, nevertheless involves the tedious and skill-required task of locating pin hole locations and drilling holes in which pins must be mounted using adhesives, heat or pressure. While U.S. Pat. No. 4,368,042 does not require two pours, it does require the use of two jaw-shaped plates, pre-molded of rigid plastic or the like. One of the plastic plates must be sawed through when an individual tooth is to be segregated.
It is also noted that the prior art is replete with various devices useful in the formation and mounting of a dental replica, but they invariably appear to be complex and costly.